Degradation behaviors of biodegradable macroporous scaffolds prepared by gas foaming of effervescent salts.

Biodegradable polymeric scaffolds for tissue engineering were fabricated by a gas-foaming/salt-leaching method using a combination of two effervescent salts, ammonium bicarbonate and citric acid. Poly(D,L-lactic-co-glycolic acid) (PLGA) in a state of gel-like paste was first produced by precipitation of PLGA dissolved in chloroform into ethanol. The polymer slurry was mixed with sieved particles of ammonium bicarbonate, molded, and then immersed in an aqueous solution of citric acid to generate macroporous scaffolds. The scaffolds had relatively homogeneous pore structures throughout the matrix and showed an average pore size of 200 microm and over 90% porosity. By adjusting the concentration of citric acid in the aqueous medium, it was possible to control porosity as well as mechanical strength of the scaffolds. In vitro degradation studies of three different scaffolds having lactic/glycolic acid molar ratios of 75/25, 65/35, and 50/50 exhibited marked swelling behaviors at different critical time points. The swollen matrices had a hydrogel-like internal structure. It was found that massive water uptake into the degrading scaffolds induced matrix swelling, which facilitated the hydrolytic scission of PLGA chains with concomitant disintegration of the matrices. Copyright 2001 John Wiley & Sons, Inc. J Biomed Mater Res 55: 401-408, 2001